It is generally known to use particulate materials such as powdered-or flaked-metal, for the production of products such as billets and extrusions. In the conventional practice, the particulate metal charge, loose or partially pre-compressed, is placed into a can-like vessel and the vessel is then sealed except for an evacuation tube for outgassing, if required. The vessel and charged metal are then heated to an elevated temperature and outgassed. After sealing off the evacuation tube, the heated vessel/metal charge combination is placed in an autoclave or other pressure-inducing receiver and subjected to an elevated fluidic or gaseous pressure frequently to the level of from 5,000 to 15,000 p.s.i.. Deformation of the sealed vessel and contained metal charge at the elevated pressure and temperature conditions, results in a consolidation of the particulate metal to a density substantially equaling the theoretical maximum density that may be achieved for the metal being processed. Afterwards, the vessel is removed from the autoclave, cooled, and opened for billet removal by longitudinal slitting and by cutting away the ends, for instance.
In another prior art practice, the particulate metal is placed in a thin closed metal can, heated to an elevated temperature, outgassed if necessary, and then placed into a thick-walled container or press receiver for consolidation and/or extrusion by a press ram. The extrusion process may involve extruding the can as well as the consolidated particulate metal. Subsequently the extruded can is removed from around the consolidated metal shape as by turning, grinding, or selective etching.
U.S. Pat. No. 4,094,672--Fleck et al. consolidates high-speed-steel-powder metal at temperatures on the order of 2000.degree. F. in a sealed can and at isostatic autoclave pressures on the order of 10,000 to 15,000 p.s.i.. Following consolidation of the contained charge, the sealed can is subjected to an interior positive pressure sufficient to cause the can to expand away from the consolidated metal. Afterwards, the end plates of the can are removed by sawing and the consolidated metal shape is withdrawn from the can through either opened end. The Fleck et al. can is stated to be reusable.
U.S. Pat. No. Re. 28,301--Havel teaches a method of consolidating and particulate metal placed in a glass can and subsequently located in a molten glass bath that is heated to a temperature approaching 2350.degree. F. and a gas pressure of 15,000 p.s.i. The vitreous can collapses upon cooling and therefore is not reused.
U.S. Pat. No. 2,123,416--Graham teaches the use of a conventional extrusion press ram, bed, and receiver (liner) equipment for consolidating and extruding particulate metals into useful shapes. The patent discloses placing the particulate metal in a closed can, heating the can and metal to an elevated temperature, either at the press station which is used to accomplish extrusion or at a station removed from the extrusion station; and subsequently extruding both the consolidated material and the can following compaction. The extruded can is either allowed to remain on the resultant extruded article as a cladding or is removed by etching or machining, for instance.
U.S. Pat. No. 3,559,271--Nilsson teaches use of a hydraulic fluid medium to pressurize a pre-compressed and pre-coated powdered-metal billet to accomplish billet extrusion. No heating of the billet to elevated temperatures is involved.
U.S. Pat. No. 3,220,199--Hanlein et al. teaches heating pre-compressed metallic powder placed in a press receiver and afterwards extruding the heated pre-compressed metal through a glass lubricated extrusion die. In instances in which a metal can is utilized to encapsulate the pre-compressed metal the can is also extruded with the metal and subsequently serves as a thin cladding.